﻿<blockquote class="extDef">NOTE&nbsp; Definition according to ISO/CD 10303-42:1992<br>
This function produces a three dimensional direction which is, with fully
defined input, the projection of arg onto the plane normal to the
z-axis. With arg defaulted the result is the projection of
(1.0,0.0,0.0) onto this plane except that if z-axis = (1.0,0.0,0.0)
then (0.0,1.0,0.0) is used as initial value of arg. A violation occurs
if arg is in the same direction as the input z-axis.</blockquote>

<blockquote class="note">NOTE&nbsp; Function adapted from <strong>first_proj_axis</strong> defined in ISO 10303-42.</blockquote>
<blockquote class="history">HISTORY&nbsp; New function in IFC1.5</blockquote>
